1. Field of the Invention
The present invention relates to an Organic Light Emitting Display (OLED), and more particularly, to an OLED and its fabrication method, in which a pixel defining layer provided on a first electrode is formed with a gas vent groove, so that a pixel edge region to which transfer is finally applied is prevented from having an untransferred portion due to gas internally remaining in a pixel and condensed when a donor film is laminated by a Laser-Induced Thermal Imaging (LITI) method, thereby decreasing edge open failures.
2. Description of the Related Art
A full-color organic light emitting diode includes a first electrode patterned on a substrate. For a bottom emission organic light emitting diode, the first electrode is a transparent electrode. For a top emission organic light emitting diode, the first electrode is of a transparent conductive material and includes a reflective layer.
A Pixel Defining Layer (PDL) is formed of an insulating material on the first electrode, thereby defining a pixel region and insulating emission layers from each other.
In the pixel region defined by the PDL, an organic layer including organic emission layers (R, G and B) is formed. Furthermore, the organic layer can further include a hole injection layer, a hole transporting layer, a hole blocking layer, an electron transporting layer, an electron injection layer, etc. The organic emission layer can be formed either of a polymer or a small molecule material.
A second electrode is formed on the organic layer. When the first electrode is a transparent electrode, the second electrode is of a conductive metal layer used as a reflective electrode. On the other hand, when the first electrode is a transparent conductive electrode including a reflective layer, the second electrode is a transparent electrode. Then, the OLED is encapsulated and completed.
In a donor film structure for a Laser-Induced Thermal Imaging (LITI) method, when the emission layer is formed by the LITI method, the donor film for the LITI method includes a base film, a light-to-heat conversion layer, and a transfer layer.
The light-to-heat conversion layer expands when laser energy is applied, so that the transfer layer also expands and is therefore separated from the donor film, thereby being transferred to a substrate of the OLED.
However, in the OLED, a remaining gas A is condensed in a pixel edge region when the donor film is laminated, so that a portion B in which a transfer has not been performed occurs. Such a failure is called ‘an edge open failure’ or ‘an untransferred failure’, which reduces the life span and performance of the display.